1. Field of the Invention
IN THE HANDLING AND TRANSPORTATION OF VARIOUS GOODS IT HAS BECOME CONVENTIONAL PRACTICE TO GROUP TOGETHER THE GOODS OR PACKAGES OF GOODS INTO UNIT LOADS CAPABLE OF BEING HANDLED BY SELF PROPELLED LIFT TRUCKS. A pallet is usually required to support and facilitate the handling of such a unit load. The most common pallets are constructed of wood strips fastened together to provide a support platform, a base and spacers connecting the platform and the base and providing openings for the entry of the forks of a lift truck.
Wooden pallets are well suited to the handling of heavy unit loads requiring the strength and durability of a wood structure, but there are many applications for which the properties of wood are not required and in which wood pallets are simply too expensive, unless reused for many different shipments at great inconvenience to the supplier and the receiver of the goods. There have been, therefore, many attempts to devise inexpensive replacements for wood pallets and the goal of such endeavors has generally been a palletlike structure of sufficient low cost to be disposable after a single use in transit and yet having sufficient integrity to provide reliable load support during handling and transportation. Although some measure of success has been achieved, the structures previously proposed have had one or more shortcomings.
2. Description of Prior Art
One example of the prior attempts made to replace wooden pallets is illustrated by the disclosure in U.S. Pat. No. 3,055,624 to R. E. Wilson, wherein it is proposed that a pallet be constructed of corrugated paperboard by the technique of cutting, folding and glueing numerous strips of material to fabricate more or less conventional components of the pallet. Although the material used is inexpensive, the technique employed is costly and the savings realized are minimal.
A somewhat simpler pallet structure made from corrugated paperboard is disclosed in U.S. Pat. No. 3,453,973 to H. Vose III, et al, but again, a rather expensive cut, fold and fasten technique is employed to provide spacer feet for the pallet.
Possibly the simplest structures thus far devised are disclosed in U.S. Pat. No. 3,763,792 to W. A. Webb and 3,776,145 to R. F. Anderson, et al. The former suggests the use of a perforated, but otherwise unadorned, corrugated sheet while the latter promotes the use of a sheet of plastic having special surface characteristics. The principal disadvantage of the structures disclosed in these two patents lies in the fact that they are not pallets, at least not substitutes for wood pallets, but are mere slip sheets and require lift trucks with special gripper devices for grasping an edge of the sheet for lifting and pulling the load onto what usually is a solid platten on the lift truck. Only a limited number of warehouse facilities are equipped with the special lift trucks of this character and the load supported by the simple slip sheet cannot be readily handled by the conventional forked lift truck.
Lastly, by way of background, attention is directed to a pallet-like structure promoted and used by the assignee of the present invention and which consisted essentially of a single sheet of corrugated paperboard having several rectangular stacks of corrugated board adhesively secured to the underside of the sheet along one edge thereof. The spaced stacks of corrugated board provided therebetween spaces for entry of the forks of a lift truck to permit the sheet and the load thereon to be lifted with the truck forks. The structure and its utilization is described in a 1964 brochure entitled "Scott Paper Company Announces Uni-Step." Usage of this system has demonstrated certain weaknesses therein attributable primarily to the flexibility, i.e. lack of structural rigidity, of the corrugated paperboard sheet. Careless handling of the lift truck while the forks were being inserted beneath the sheet and load often resulted in the forks piercing the sheet and the load with consequent damage to the load. Secondly, a lift truck equipped with a multiplicity of forks, usually six, was required to prevent undesirable displacement of the components of the load during lifting because the pallet sheet offered substantially no beam support for anything but very light loads.